[Bug c++/121068] Placement new of array element is rejected at compile-time

[tkaminsk at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121068

--- Comment #16 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
Ah sorry, I was sure I posted the function before:
```
#include <new>

struct S
{
  constexpr S() = default;
  constexpr S(int x) : s(x) {}
  constexpr S(S&& x) : s(x.s) {}                                                
  constexpr S& operator=(S&& x) { s = x.s; return *this; }                      
  unsigned char s;                                                              
};

constexpr
int foo()
{
  union { S a[20]; };
  new (&a) S[20](); // OK
  for (int i = 0; i < 20; ++i)
    a[i].~S();

  auto* sf = ::new(&a[2]) S(11);
  return 1;
}

static_assert(foo());

constexpr
int foo2()
{
  union { S a[20]; };
  new (&a) S[20]; // ILL-FORMED
  for (int i = 0; i < 20; ++i)
    a[i].~S();

  auto* sf = ::new(&a[2]) S(11);
  return 1;
}

static_assert(foo2());
```
https://godbolt.org/z/cKbEsdzEh